In accordance with the development of technology, electronic devices such as mobile phones, home appliances, personal computers (PC), personal digital assistants (PDA), liquid crystal displays (LCD), and the like, have changed from utilizing an analog scheme to utilizing a digital scheme, while the speeds of electronic devices have increased due to an increase in an amount of data required to be processed.
Therefore, universal serial bus (USB) 2.0, USB 3.0, and a high-definition multimedia interface (HDMI) have become widespread examples of high speed signal transmitting interfaces and are currently used in many digital devices, such as personal computers and digital high-definition televisions.
These high speed interfaces use a differential signal system, transmitting differential signals (differential mode signals) using a pair of signal lines, unlike a single-end transmitting system that has been generally been used in the related art.
However, electronic devices that have been digitized implemented with higher speeds are sensitive to external stimuli, such that distortion of signals due to high frequency noise has often occurred.
A switching voltage generated in a circuit, power noise included in a power supply voltage, an unnecessary electromagnetic signal or electromagnetic noise, and the like, may be causes of such abnormal voltage and noise, and a common mode filter (CMF) has been used as a unit for preventing the above-mentioned abnormal voltage and high frequency noise from being introduced into the circuit.
Recently, in accordance with miniaturization and improvements in the performance of mobile components, it has been required to decrease a size of the common mode filter, while securing predetermined levels or more of performance and reliability in the common mode filter, even when the common mode filter is miniaturized, has been demanded.
For example, in accordance with a decrease in a size of a component, a size of an external electrode mounted on an SET substrate and electrically connected to the SET substrate, as well as a size of an internal coil of the common mode filter has been decreased. Therefore, a defect such as breakage of a connection portion between the internal coil and the external electrode or an increase in a level of resistance of the connection portion may occur after a reliability test or during an SET operation.